Making a Real-Time Operating System for the Raspberry Pi 2B

Real-Time Operating Systems are used in a variety of applications ranging from autonomous vehicles, flight controllers, and energy management systems to pacemakers, satellite tracking systems, amateur robotics and much more. It turns out that while general-purpose computers can perform tasks quite quickly, the execution time for various processes varies noticeably between different executions. Execution time variation poses a big challenge for many computer-controlled systems that operate in the real-world such as robots, autonomous vehicles, drones, traffic signals, etc. The execution time variation matters in these systems since they must interact in the real world and perform actions at the proper times, and executing these tasks at other times can have varied effects ranging from a minor inconvenience to catastrophic failure. Many of these real-time systems are comprised of single board computers, such as a pacemaker. One single-board computer that is popular among hobbyists due to its form factor, cost, and performance is the Raspberry Pi, which uses an ARM-based processor. In order to provide a Real-Time Operating System for this single board computer this paper presents Jobbed, a single-core Real-Time Operating System which uses a fixed priority preemptive scheduler, targeted at the Raspberry Pi 2B. In this paper, we present the algorithmic structure behind this system and compare it to the Raspbian Operating System in an array of performance and behavioral tests targeted towards proper Real-Time Operating Systems.